Butadiene polymerization catalyst

ABSTRACT

Ziegler-type hydrocarbon-soluble catalyst systems for the polymerization of conjugated diolefins, or mixtures thereof, to obtain high molecular weight polymers possessing varying proportions of trans-1,4 units, in the range of 50-90%. The catalyst systems are based on a non-reduced salt of titanium, an organometallic compound, and an iodine-containing compound, or iodine corresponding to the generalized formula Ti(halide) 4  -M n  I m  -AlR a  X 3  -a, where M is aluminum or tetravalent tin, n is 0 or 1, m is the valence of M and where n is 0, m is 2, X is Cl, Br or I, a is 2 to 3, R is alkyl, halide is Cl, Br or I, and where halide is I, M n  I m  may be omitted.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. application Ser. No. 392,966,filed Aug. 30, 1973 now U.S. Pat. No. 3,865,749.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a catalyst system and a process for usingsame, useful for the stereospecific polymerization of butadiene. Morespecifically, the catalyst comprises an organoaluminum compound, a Lewisbase, and a Ti(+4) halogen - M_(n) I_(m) composition. This catalystsystem is useful in the production of polybutadiene homopolymers orcopolymers in which the ratio of trans-1,4 to cis-1,4 units can bevaried over wide limits and especially within the particularly desirabletrans-1,4 range of 50 to 90% of total unsaturation.

2. Description of the Prior Art

Ziegler-type multi-component catalyst systems such as transition metalhalides combined with organo metallic compounds have been known for wellover a decade. The ability of such catalysts to polymerize butadiene toelastomeric products has also been recognized, but the polymers thusproduced have generally been characterized by high cis-1,4 contentrather than trans-1,4 addition units. Thus, for example, in U.S. Pat.No. 3,471,461, there is disclosed the use of TiX₃.nAlI₃ -xAl(alkyl)₃catalyst systems for the polymerization of butadiene, in which thesteric arrangement of the polybutadiene is predominantly that resultingfrom cis-1,4 addition.

Other catalysts, particularly based on vanadium compounds, capable ofproducing polybutadienes containing more than 90% trans-1,4 additionunits have also been developed, but the polymers thus produced have beencharacterized by resinous or plastic rather than elastomeric properties.

We had previously discovered that certain trivalent titanium halidecatalyst systems, used in conjunction with particular bases, producedpolybutadienes containing a predominant amount of 1,4-addition units.These catalyst systems are taught in U.S. pat. No. 3,663,450 and U.S.Pat. No. 3,779,944.

In U.S. Pat. No. 3,663,450, a partially reduced titanium halide, notablyTiCl₃, is precomplexed with a Lewis base and forms a final catalystcapable of producing high cis-1,4 polybutadiene, while in U.S. Pat. No.3,779,944 the Lewis base is not precomplexed with the titanium halidecomponent and may be added to the polymerization zone in any order withrespect to the latter component. This difference is important in that itprovides for the production of polybutadienes having variable amounts oftrans-1,4 addition units, up to about 90% in the polymer.

It is also known that certain titanium tetrahalides are useful inpolymerizing butadiene. Generally, they produce polybutadienescontaining 85-95% cis-1,4 addition units. Typical of these are a seriesof iodine-containing catalyst systems, such as TiI₄ -AlR₃, TiX₄ -I₂-AlR₃, and TiX₄ -AlI₃ -AlR₃, where X is chlorine or bromine. Thesesystems have been published in several patents. See Belgian Patent551,851; Belgian Patent 602,496; U.S. Pat. No. 3,245,976, and BritishPatent 1,138,840.

Previously, when Lewis bases were added to titanium tetrahalide-typecatalysts in amounts necessary to effect a noticeable change in thestereochemistry of the polymerization reaction, there was always anaccompanying drastic decrease in the polymerization rate and catalystefficiency.

The inventors have now found surprisingly that the addition of certainLewis bases to a general catalyst system comprised of an organoaluminum,having the formula AlR_(a) X_(3-a), and a Ti(+4) halide - M_(n) I_(m)composition causes a decrease in the cis-1,4 addition of the butadienemonomer and a corresponding increase in the trans-1,4 addition withoutthe catalyst efficiency being adversely affected to any significantextent.

The inventors have also found that the novel catalyst system is capablenot only of efficiently producing polybutadienes containing largerproportions of trans-1,4 addition units than those titanium basedcatalysts disclosed in the prior art, but also of producingpredominantly elastomeric polybutadienes containing 50-90% of suchunits. This is a particularly surprising and significant discovery. Suchpolymers of corresponding over-all compositions which have been preparedin the past with the help of other catalysts or polymerization methodshave generally exhibited a considerable amount of crystallinity andplastic character. While the inventors do not wish to be bound by anyparticular explanation for the difference in physical properties betweenthe 50-90% trans-1,4 polybutadienes prepared according to this inventionand those of the prior art, it is believed that the much moreelastomeric character of the former is the consequence of the morerandom distribution of the cis-1,4 and trans-1,4 units in the polymermolecules than in the polymers heretofore known.

The purpose of this invention therefore is to provide a new catalyst forcontrolling the steric configuration of the 1,4 addition units ofpolymers of conjugated dienes, and copolymers thereof, and a process foremploying same to produce such polymers and in particular to apolybutadiene containing a high percentage of trans-1,4 addition unitsand having predominantly elastomeric properties.

SUMMARY OF THE INVENTION

In general, this invention relates to a catalyst system broadlybelonging to the Ziegler group, comprising a non-reduced salt oftitanium, an organometallic compound and an iodine-containing compoundor iodine corresponding to the generalized formula

    Ti(halide).sub.4 --M.sub.n I.sub.m --AlR.sub.a X.sub.3-a   (1)

where the halide may be I, Cl, or Br. When the halide is I, M_(n) I_(m)may be omitted. M is either aluminum or tin (+4), n is 0 or 1, and m isthe valence of M and when n=0, m=2. In the organoaluminum component, Ris an alkyl having 1 to 12 carbon atoms, X is Cl, Br, or I and a is anynumber from 2 to 3.

To the basic catalyst system is added certain Lewis bases such astetrahydrothiophene, tetrahydrothiopyran, 2-methyl tetrahydrothiophene,tetrahydrofuran, tetrahydropyran, 2,5-dimethyl tetrahydrofuran, and thelike. The ratio of Lewis base to titanium in the catalyst mixturecontrols the steric arrangement of the monomer units, and may range from1:1 to 500:1, depending upon the amount of trans-1,4 structural unitsdesired in the polybutadiene.

Particular examples of the titanium halide -M_(n) I_(m) component are:

    TiI.sub.4                                                  (II)

    tiX.sub.4 --I.sub.2,                                       (III)

where X is Cl or Br

    TiX.sub.4 --AlI.sub.3,                                     (IV)

where X is Cl or Br

    TiX.sub.4 --SnI.sub.4,                                     (V)

where X is Cl or Br

PREFERRED EMBODIMENTS

The catalyst system of this invention is principally useful for thepolymerization of conjugated diolefin monomers, such as 1,3-butadiene.However, the catalysts are also useful for forming copolymers ofconjugated dienes with other olefin monomers.

The Lewis bases that may be used are heterocyclic thia, aza and oxacompounds, specifically cyclic thioethers, cyclic ethers, and theirderivatives. Such compounds include tetrahydrothiophene,tetrahydrothiopyran, tetrahydrofuran, tetrahydropyran, 2,5-dimethyltetrahydrofuran, 3-phenyl tetrahydrofuran, 3-ethyl-4-propyltetrahydrofuran, 2,5-dimethyl-3-chloro tetrahydrofuran, 2-methyltetrahydrothiophene, 3-phenyl tetrahydrothiophene, 3-ethyl-4-propyltetrahydrothiophene and 2,5-dimethyl-3-chloro tetrahydrothiopyran.Particularly preferred among these compounds is tetrahydrothiophene;however, other cyclic thioethers may also be advantageously employed.

As a general rule, the higher the concentration of the Lewis base in thepolymerization zone, the higher will be the trans-1,4 content of thepolymer until a certain upper limit has been reached. Thus, from 50-90%of the resulting polybutadiene may be of the trans-1,4 configuration.

The organoaluminum compounds that can be advantageously used for makingthe catalysts of this invention are trialkylaluminums, such astrimethylaluminum, triethylaluminum, triisobutylaluminum,trihexylaluminum, triisoprenylaluminum, etc. Mixtures oftrialkylaluminums and dialkylaluminum halides and alkoxides may also besuccessfully employed. Among suitable dialkylaluminum compounds to beused in conjunction with trialkylaluminums may be mentioneddialkylaluminum halides, particularly dialkylaluminum iodides,dialkylaluminum alkoxides, etc.

The hydrocarbon diluents used in making the polybutadiene of the presentinvention should be liquids at the conditions of temperature andpressure used in the polymerization reaction. Suitable diluents includeC₄ to C₁₀ saturated aliphatic or cycloaliphatic hydrocarbons, such asn-butene, n-pentane, n-heptane, isooctane, n-decane, cyclohexane,methylcyclohexane, etc. and aromatic compounds such as benzene, toluene,xylene, tetralin isopropyl benzene, etc. In a batch polymerization, thediluent can be added to the reaction zone either prior to, with, orsubsequent to the monomer. The same holds true for the aluminum alkylcomponent.

However, when AlI₃ or SnI₄ is used as a component of the catalyst(species IV and V, respectively), they are normally added prior toaddition of monomer and aluminum alkyls.

The Lewis base may be added to the polymerization zone in virtually anysequence with the other ingredients, but it is generally preferably toadd at last the Ti(halide)₄ and monomer before adding the Lewis base.However, in a continuous process, the base would normally be added witheither the monomer or the aluminum alkyl. In such a continuous system,the titanium tetrahalide along with solvent and either I₂, AlI₃ or theSnI₄, depending on the particular catalyst combination used, would beadded as a mixture to the reactor.

While the TiX₄ -nAlI₃ -xAlR₃ and Lewis base may be combined in manydifferent ways to produce an active polymerization catalyst, aparticularly preferred embodiment of this invention involves firstdissolving the TiX₄ -nAlI₃ component in all or part of thepolymerization diluent or solvent, then adding the monomer and finallyadding the AlR₃ and the Lewis base. Alternatively, the TiX₄ -nAlI₃ maybe added to the polymerization diluent containing the monomer whereuponthe AlR₃ and the Lewis base may be added to form the complete catalystand start the polymerization. Although the Lewis base may besuccessfully added before the trialkylaluminum, better results areusually obtained if the Lewis base is added either together with orafter the trialkylaluminum, especially when the base is to be employedin the rather large concentrations required for production of polymerscontaining a predominant amount of trans-1,4 units. In such cases thebase seems to interfere with and slow down the reaction between thealkyl metal and the TiX₄ -nAlI₃ component required for formation of thecatalytically active species. By properly utilizing the latter mode ofbase addition, i.e., by adding the base after the polymerization hasbeen initiated with the unmodified TiX₃ -nAlI₃ -xAlR₃ catalyst system,it may actually be possible to obtain A-B type block copolymers in whichthe first (A) block has the high cis-1,4 structure characteristic of thepolybutadienes made with the unmodified catalyst system and the second(B) block has the higher trans-1,4 structure characteristic of thepolybutadienes made with the modified catalyst system. In this instanceand in subsequent use, the term "modifier" refers to the Lewis base. Onthe other hand, if the Lewis base is added immediately after the AlR₃,the polymerization may be initiated rapidly without any significantamount of rather pure cis-1,4 polybutadiene blocks being formed. Hence,this method is particularly suitable for the production of hightrans-1,4 polybutadiene.

The same considerations are applicable to the catalyst species which useI₂ or SnI₄.

The total amount of catalyst employed in the polymerization of butadienemay vary within rather wide limits depending upon the particularconditions of polymerization, but is generally in the range of fromabout 0.001 to about 0.5 wt. %, preferably 0.01 to 0.2 wt. % based uponthe total reaction mixture comprising the butadiene monomer to bepolymerized and the reaction diluent.

In general, it will be found that, for the same catalyst composition,the molecular weight of the polymer decreases as the catalystconcentration is increased, provided, of course, that all the otherconditions are kept constant, e.g., monomer concentration, temperatureof polymerization, etc. Thus, variation in the amount of catalystemployed per unit of monomer may advantageously be used to control themolecular weight of the polymer obtained. Other factors, such as Al/Tiratio, polymerization temperature, and the addition of chain transferagents, can be used advantageously to control the molecular weight ofthe polymer product of the invention.

In component III (TiX₄ -I₂), the molar ratio of TiX₄ to I₂ can vary fromabout 1:1 to about 1:20. The preferred range is from about 1:1 to about1:5. In Component II (TiI₄) and Component III, the molar ratio ofaluminum alkyl to TiX₄ ranges from about 20:1 to about 1:1, morepreferably from about 10:1 to about 2:1.

In Component IV (TiX₄ -AlI₃), the preferred molar ratio of TiX₄ /AlI₃ isin the range of about 1:1 to about 1:10 and the ratio of AlR₃ to (TiX₄-AlI₃) is preferably in the range of about 1.5:1 to about 4.5:1 and mostpreferably in the range of about 2:1 to about 4:1. The same holds truefor Component V (TiX₄ -SnI₄).

For any given molar concentration of the titanium component, the ratioof Lewis base to titanium in the catalyst mixture controls the stericarrangement of the monomer units in the resulting polybutadiene and, ingeneral, the greater the concentration of Lewis base employed, thehigher the trans-1,4 content in the polymer up to a certain upper limit.Thus, to otain the same proportion of trans-1,4 unsaturation indifferent polymerizations involving varying concentrations of thetitanium component, one will have to increase the ratio of Lewis base totitanium compound as the concentration of the latter is decreased. Themolar ratio of Lewis base to titanium compound may vary from about 1:1to about 500:1 depending upon the amount of trans-1,4 structural unitsdesired in the polybutadiene and the concentration of the titaniumcomponent. Preferably, the molar ratio of Lewis base to titanium rangesfrom about 10:1 to about 200:1.

The conditions of the polymerization reaction can vary over a widerange. Generally, temperatures ranging from less than 0°C to about 100°Ccan be used; however, temperatures ranging from 5° to 100°C arepreferred. Pressures ranging from subatmospheric to about 10 atmospherescan be employed depending primarily upon the vapor pressure of the dieneand diluent in the polymerization reaction. A preferred range would,however, be from atmospheric to about 5 atmospheres. Reaction timesranging from a minute to 250 hours can be utilized depending primarilyon the time needed for the desired monomer conversion under thepolymerization conditions used; however, it is usually possible toachieve close to the maximum conversion obtainable in 24 hours or less.

The reaction vessel used for the polymerization can be constructed fromany material that is inert to the reactants and is capable ofwithstanding the operating pressures. Reactors made of glass, stainlesssteel and glass lined steel may thus be employed.

Upon completion of the polymerization, the catalyst is deactivated bythe addition of a small quantity of a suitable deactivating agent, suchas a lower alkanol or a solution of an alkoxide of an alkali or alkalineearth metal, e.g., sodium isopropoxide, sodium ethoxide, potassiumt-butoxide, etc. The polymer formed may be recovered from thepolymerization mixture by standard techniques such as removal of thediluent by steam distillation or by addition of an anti-solvent toprecipitate the polymer. The solid polymer obtained is then isolated byfiltration, centrifugation, or similar methods.

The molecular weights, expressed as viscosity average molecular weight,of the butadiene polymers of the present invention range upwards from100,000 and preferably from 150,000 to 3,000,000. The butadiene polymerscontain reactive unsaturation and may be cured to form highly usefulvulcanized materials of varying properties. Any one of a wide variety ofcuring procedures may be employed, such as sulfur curing or free radicalcuring.

In the uncured state, the instant butadiene polymers exhibit tensilestrengths of the order of 150 to 2000 psi, with % elongation up to about1300. The percent permanent set after breaking ranges from about 25 toabout 300.

In the cured state, the instant butadiene polymers exhibit tensilestrengths of the order of 1200 to 2500 psi, with % elongation up toabout 900.

The polymers of this invention have many varied uses. They may beemployed in the preparation of tires, inner tubes, hose and tubing, wireand cable coatings, as well as for a wide variety of coated or moldedarticles. Those polymers having from 70-90% trans unsaturation areparticularly suitable for the preparation of injection-molded articlesand possess thermoelastic properties.

This invention and its advantages will be better understood by referenceto the following examples.

EXAMPLES 1-4

A number of butadiene polymerizations were carried out withtetrahydrothiophene (THT) modified TiCl₄ -I₂ catalyst systems, usingaluminum triethyl as the aluminum alkyl. The polymerizations werecarried out inside a nitrogen containing dry box in capped 1/2 gallonjars equipped with magnetic stirrers. The TiCl₄, and 100g. of monomerwere added to the reaction vessel, to which 450 ml benzene had firstbeen added.

The AlEt₃ and I₂, which has been dissolved in 50 ml of benzene, werethen added to the reactor followed immediately by the THT. Thepolymerizations were conducted at room temperature. Actual quantities ofcatalyst components, etc. and reaction times are shown in Table I, alongwith the results of the experiments.

The polymerizations were terminated by decomposition of the catalystthrough the addition of 30 ml of a 0.2M solution of sodium isopropoxidein isopropanol. One-half gram of N-phenyl-2-naphthylamine dissolved in500 ml benzene was then added as an oxidation inhibitor to the reactionmedium, whereupon the polymer solution was transferred to an open panand the polymer recovered by evaporation of the diluent, first atatmospheric pressure and room temperature and then in vacuo at about50°C.

As shown by the results in the table, the unmodified, i.e., THT free,catalysts produced high mol. wt. polybutadiene containing about 90%cis-1,4 addition units. All of the modified catalysts on the other handproduced polymers with a preponderant amount of trans-1,4 additionunits, up to about 80%.

                                      TABLE I                                     __________________________________________________________________________    TiCl.sub.4 -I.sub.2 -AlR.sub.3 -THT CATALYST SYSTEM                           (100g. Butadiene, 500 ml Benzene, Room Temp.)                                 Catalyst       1         2     3         4                                    __________________________________________________________________________    TiCl.sub.4, mg ----------                                                                          19.0                                                                              ----------                                                                          ----------                                                                          19.0  ----------                         I.sub.2, mg    ----------                                                                          50.8                                                                              ----------                                                                          ----------                                                                          50.8  ----------                         AlE.sub.3, mg  ----------                                                                          57.1                                                                              ----------                                                                          ----------                                                                          68.5  ----------                         THT, mg        0         617   0           441                                AlEt.sub.3 /TiCl.sub.4 (molar ratio)                                                         5         5     6           6                                  I.sub.2 /TiCl.sub.4 (molar ratio)                                                            2         2     2           2                                  THT/TiCl.sub.4 (molar ratio)                                                                 0         70    0           50                                 Reaction Time (hrs.).sup.(a)                                                                 18.5      67    18.5        116                                Results                                                                       Polymer Yield, %                                                                             72.2      59.1  89.7        71.9                               Polymer mol. wt. ×  10.sup.-.sup.3(b)                                                  435       185   460         225                                Polymer unsaturation                                                           Vinyl, %      5.2       9.0   5.0         11.9                                Cis, %        88.6      12.9  90.9        15.9                                Trans, %      6.2       78.1  4.1         72.2                               __________________________________________________________________________     .sup.(a) Complete reaction often occurred within a period of time             considerably shorter than those indicated in the table.                       .sup.(b) According to the correlation of Johnson and Wolfangel, Ind. Eng.     Chem., 44, 752 (1952).                                                   

EXAMPLES 5-10

A number of butadiene polymerizations were carried out with THT,aluminum triethyl, TiCl₄, and I₂, according to the general procedure ofExamples 1-4 but with differences in the order of addition of thevarious components.

The order of addition was:

    Run 5 TiCl.sub.4   monomer (1,3-butadiene)-AlEt.sub.3 -I.sub.2.                                  [no THT]                                                   Run 6 TiCl.sub.4   monomer-AlEt.sub.3 +THT premixed in                                           50 ml benzene, I.sub.2.                                    Run 7 TiCl.sub.4, I.sub.2                                                                        monomer, AlEt.sub.3 dissolved in                                              50 ml benzene.                                             Run 8 same as 7    but with the THT added together                                               with the AlEt.sub.3.                                       Run 9 AlEt.sub.3, TiCl.sub.4 +I.sub.2                                                            premixed in 50 ml benzene-                                                    monomer.                                                   Run 10                                                                              same as 9    except that THT was added after                                               the monomer.                                           

As the total amount of benzene used as diluent was 500 ml, 450 mlbenzene was added at the beginning in Runs 6-10, while 500 ml was addedat the beginning in Run 5.

The reactions were terminated, and product recovered, in the same manneras in Examples 1-4.

The results of the experiments are shown in Table II. It is apparentthat the addition of THT causes a marked change in the stereospecificityfrom predominantly cis-1,4 to predominantly trans-1,4 addition.

                                      TABLE II                                    __________________________________________________________________________    TiCl.sub.4 -I.sub.2 -AlR.sub.3 -THT                                           Butadiene Catalyst System                                                     (100g. Butadiene, 500 ml Benzene, Room Temperature)                           Catalyst       5     6     7     8     9     10                               __________________________________________________________________________    TiCl.sub.4, mg 19.0  19.0  19.0  19.0  19.0  19.0                             I.sub.2, mg    101.5 101.5 50.8  50.8  50.8  50.8                             AlEt.sub.3, mg 114.2 114.2 79.9  79.9  79.9  79.9                             THT, mg        0     441   0     441   0     529                              I.sub.2 /TiCl.sub.4 (molar ratio)                                                            4     4     2     2     2     2                                THT/TiCl.sub.4 (molar ratio)                                                                 0     50    0     50    0     60                               AlEt.sub.3 /TiCl.sub.4 (molar ratio)                                                         10    10    7     7     7     7                                Reaction Time (hrs).sup.(a)                                                                  18.5  19    69    18    67.5  42                               Results:                                                                      Polymer yield, %                                                                             70.4  67.2  83.6  55.2  91.7  53.9                             Polymer mol. wt. × 10.sup.-.sup.3(b)                                                   225   230   400   275   365   350                              Polymer unsaturation                                                           Vinyl, %      5.3   4.2   5.0   7.9   4.9   2.5                               Cis, %        87.1  23.7  88.2  15.1  91.5  12.3                              Trans, %      7.6   72.0  6.8   77.0  3.6   85.2                             __________________________________________________________________________     .sup.(a) See Table I.                                                         .sup.(b) See Table I.                                                    

EXAMPLE 11

When butadiene is polymerized in the same manner as in Example 2,substituting tetrahydrothiopyran for THT, the recovered polybutadienehas a trans-1,4 configuration of up to about 80%. The polybutadiene isrecovered in good quantities and has a molecular weight in excess of150,000 (as determined by the correlation of Johnson and Wolfangel, Ind.Eng. Chem., 44, 752 (1952).)

EXAMPLES 12-18

A series of polymerization experiments were conducted to prepare hightrans-1,4 content polybutadiene. The catalyst system was TiCl₄, AlI₃,aluminum triethyl (AlEt₃), and tetrahydrothiophene (THT).

All polymerizations were carried out with capped 1/2 gallon jarsequipped with magnetic stirrers, the jars being inside anitrogen-containing dry box. The order of addition of the variouscomponents was benzene, TiCl₄, AlI₃ and butadiene followed by AlEt₃,which was added either alone or mixed with THT as indicated in TableIII.

The polymerizations were terminated by decomposition of the catalystthrough the addition of 30 ml of a 0.2M solution of sodium isopropoxidein isopropanol. One-half gram of N-phenyl-2-naphthylamine dissolved in500 ml benzene was then added as an oxidation inhibitor to the reactionmedium, whereupon the polymer solution was transferred to an open panand the polymer recovered by evaporation of the diluent, first at roomtemperature and atmospheric pressure and then in vacuo at about 50°C.

The interesting physical properties of polymers prepared according tothis invention are reported in U.S. patent application Ser. No. 175,758,filed Aug. 27, 1971, which describes the preparation of similar polymersbut with a different catalyst system.

EXAMPLES 19-22

Four runs were made following the procedure of Examples 12-18,substituting TiBr₄ for the TiCl₄.

The details of the experiments and the results are shown in Table IV.

                                      TABLE III                                   __________________________________________________________________________    EFFECT OF THT ADDITION OF BUTADIENE POLYMERIZATION WITH TiCl.sub.4            -xAlI.sub.3 -yAlR.sub.3 CATALYSTS                                             (100 g butadiene, 500 ml benzene, room temp.)                                                 12    13    14    15    16    17    18                        Catalyst                                                                      __________________________________________________________________________    TiCl.sub.4, mg  ------------------ 19.0 ------------------                                                            ------------ 19.0 ------------        AlI.sub.3, mg   ------------------ 122.3 ------------------                                                           ------------ 204.0 ------------       AlEt.sub.3, mg.sup.(a)                                                                        ------------------ 102.7 ------------------                                                           ------------ 137.0 ------------       THT, mg.sup.(a) --    264.6 441   617   --    441   705.4                     AlEt.sub.3 /AlI.sub.3 /TiCl.sub.4 molar ratio                                                 -------------------- 9/3/1 --------------------                                                       ------------ 12/5/1 ------------      THT/TiCl.sub.4 molar ratio                                                                    0     30    50    70    0     50    80                        Reaction Time, hrs.sup.(b)                                                                    191/2 20    19    67    67    20    20                        Results                                                                       Polymer yield, %                                                                              89.6  73.7  79.7  81.7  87.2  84.0  80.7                      Polymer mol. wt. × 10.sup.-.sup.3(c)                                                    235   205   235   225   135   175   185                       Polymer unsaturation                                                           Vinyl, %       5.3   9.7   7.1   6.3   5.7   5.2   5.2                        Cis, %         87.1  36.9  20.2  13.8  79.3  27.6  14.5                       Trans, %       7.6   53.4  72.7  79.9  15.0  67.2  80.3                      __________________________________________________________________________     .sup.(a) AlEt.sub.3 and THT were premixed before being added to reaction      mixture.                                                                      .sup.(b) Complete reaction usually occurred within a period of time much      shorter than those indicated in the table.                                    .sup.(c) According to the correlation of Johnson and Wolfangel, Ind. Eng.     Chem., 44, 752 (1952).                                                   

                                      TABLE IV                                    __________________________________________________________________________    EFFECT OF THT ADDITION ON BUTADIENE POLYMERIZATION                            WITH TiBr.sub.4 -xAlI.sub.3 -yAlR.sub.3 CATALYSTS                             (100 g butadiene, 500 ml benzene, room temp.)                                                 19          20    21          22                              Catalyst                                                                      __________________________________________________________________________    TiBr.sub.4, mg  ----------                                                                           36.8 ----------                                                                          ----------                                                                           36.8 ----------                      AlI.sub.3, mg   ----------                                                                          122.3 ----------                                                                          ----------                                                                          204.0 ----------                      AlEt.sub.3, mg.sup.(a)                                                                        ----------                                                                          102.7 ----------                                                                          ----------                                                                          137.0 ----------                      THT, mg.sup.(a) 0           70    0           60                              AlEt.sub.3 /AlI.sub.3 /TiBr.sub.4 molar ratio                                                 ----------                                                                          9/3/1 ----------                                                                          ----------                                                                          12/5/1                                                                              ----------                      THT/TiBr.sub.4  molar ratio                                                                   0           70    0           60                              Reaction Time, hrs.sup.(b)                                                                    91          171/2 19          91                              Results                                                                       Polymer yield, %                                                                              83.8        80.8  85.5        80.1                            Polymer mol. wt. × 10.sup.-.sup.3(c)                                                    210         265   120         300                             Polymer unsaturation                                                           Vinyl, %       5.2         8.4   5.5         3.8                              Cis, %         84.9        16.5  77.4        23.1                             Trans, %       9.9         75.1  17.1        73.1                            __________________________________________________________________________     .sup.(a) AlEt.sub.3 and THT were premixed before being added to the           reaction mixture.                                                             .sup.(b) Complete reaction usually occurred within a period of time much      shorter than those indicated in the table.                                    .sup.(c) According to the correlation of Johnson and Wolfangel, Ind. Eng.     Chem., 44, 752 (1952).                                                   

EXAMPLES 23-28

Following the procedures and using the equipment of Examples 1-4, aseries of experiments were conducted using the catalyst system:

    TiX.sub.4 -SnI.sub.4 -AlR.sub.3

with tetrahydrothiophene. Both TiCl₄ (Examples 23-26) and TiBr₄(Examples 27 and 28) were used.

The polybutadiene was recovered in the same manner as previouslydescribed in Examples 1-4. The results are shown in Table V.

                                      TABLE V                                     __________________________________________________________________________    EFFECT OF THT ADDITION OF BUTADIENE POLYMERIZATION WITH TiX.sub.4             -xSnI.sub.4 -yAlR.sub.3 CATALYSTS                                             (100 g butadiene, 500 ml benzene, room temp.)                                                 23        24   25        26   27        28                    Catalyst                                                                      __________________________________________________________________________    TiCl.sub.4, mg  --------                                                                            19.0                                                                              --------                                                                           --------                                                                            19.0                                                                              --------                                                                           --------                                                                           --   --------              TiBr.sub.4, mg  --------                                                                           --   --------                                                                           --------                                                                           --   --------                                                                           --------                                                                           36.8 --------              SnI.sub.4, mg   --------                                                                           125.3                                                                              --------                                                                           --------                                                                           187.9                                                                              --------                                                                           --------                                                                           187.9                                                                              --------              AlEt.sub.3, mg.sup.(a)                                                                        --------                                                                           102.7                                                                              --------                                                                           --------                                                                           137.0                                                                              ------ --                                                                          --------                                                                           137.0                                                                              --------              THT, mg.sup.(a) --        529.0                                                                              --        617.2                                                                              --        441.0                 AlEt.sub.3 /SnI.sub.4 TiXhd 4 molar ratio                                                     --------                                                                           9/2/1                                                                              --------                                                                           --------                                                                           12/3/1                                                                             --------                                                                           --------                                                                           12/3/1                                                                             --------              THT/TiX.sub.4 molar ratio                                                                     0         60   0         70   0         50                    Reaction Time, hrs.sup.(b)                                                                    191/2     181/2                                                                              191/2     181/2                                                                              91        18                    Results                                                                       Polymer yield, %                                                                              76.3      80.8 75.2      81.9 82.9      72.5                  Polymer mol. wt. × 10.sup.-.sup.3(c)                                                    230       270  185       235  145       250                   Polymer unsaturation                                                           Vinyl, %       5.2       5.8  5.4       3.4  5.0       3.5                    Cis, %         88.1      16.8 87.0      14.7 87.9      23.9                   Trans, %       6.7       78.4 7.6       81.9 7.1       72.6                  __________________________________________________________________________     .sup.(a) AlEt.sub.3 and THT were premixed before being added to the           reaction mixture.                                                             .sup.(b) Complete reaction usually occurred within a period of time much      shorter than those indicated in the table.                                    .sup.(c) According to the correlation of Johnson and Wolfangel, Ind. Eng.     Chem., 44, 752 (1952).                                                   

EXAMPLES 29-33

In Belgian Patent 551,851, it is shown that a catalyst system comprisingTiI₄ and a trialkyl aluminum polymerize 1,3-butadiene to yield apolybutadiene having 85-95% cis-1,4 configuration.

To show the unique advantage of the present invention, i.e., use of aLewis base to modify the steric configuration of butadiene basedpolymers, a series of experiments were conducted polymerizing1,3-butadiene. The catalyst system used was TiI₄ -AlR₃ usingtetrahydrothiophene (THT). The mole ratio of THT to TiI₄ was varied from10 up to 30. The Al triethyl (AlEt₃) and THT were premixed beforeaddition to the reactor.

The polymerization was terminated and polymer recovered in the samemanner as used in Examples 1-4.

The results are shown in Table VI.

EXAMPLES 34-40

Several butadiene-1,3 polymerizations were conducted with the catalystsystem and procedure of Examples 29-33, above. However, the THT wasadded to the reaction mixture after the AlEt₃. Results are in Table VII.

                                      TABLE VI                                    __________________________________________________________________________    EFFECT OF THT ADDITION ON BUTADIENE POLYMERIZATION                            WITH TiI.sub.4 BASED CATALYSTS                                                (100 g butadiene, 500 ml benzene, room temp.)                                 Catalyst        29    30    31    32    33                                    __________________________________________________________________________    TiI.sub.4, mg   ------------------ 111 ------------------                                                             167                                   AlEt.sub.3, mg.sup.(a)                                                                        ------------------ 68.5 ------------------                                                            102.8                                 THT, mg         0     176.3 352.7 529.0 793.5                                 AlEt.sub.3 /TiI.sub.4 molar ratio                                                             -------------------------- 3 --------------------------       THT/TiI.sub.4 molar ratio                                                                     0     10    20    30    30                                    Reaction Time, hrs.sup.(b)                                                                    19    19    20    201/2 183/4                                 Results                                                                       Polymer yield, %                                                                              83    86.6  83.7  78.4  90.5                                  Polymer mol. wt. × 10.sup.-.sup.3(c)                                                    240   205   425   295   445                                   Polymer unsaturation                                                           Vinyl, %       4.6   5.7   5.0   4.3   3.6                                    Cis, %         91.3  62.3  34.7  22.1  13.7                                   Trans, %       4.1   32.0  60.4  73.6  82.7                                  __________________________________________________________________________     .sup.(a) AlEt.sub.3 and THT were premixed before being added to the           reaction mixture.                                                             .sup.(b) Complete reaction usually occurred within a period of time much      shorter than those indicated in the table.                                    .sup.(c) According to the correlation of Johnson and Wolfangel for cis-1,     poly-butadiene, Ind. Eng. Chem., 44, 752 (1952).                         

                                      TABLE VII                                   __________________________________________________________________________    EFFECT OF THT ADDITION ON BUTADIENE POLYMERIZATION                            WITH TiI.sub.4 BASED CATALYSTS                                                (100 g butadiene, 500 ml benzene, room temp.)                                 Catalyst        34    35    36    37    38    39    40                        __________________________________________________________________________    TiI.sub.4, mg   -------------------------------------- 111                                    --------------------------------------                        AlEt.sub.3, mg  57.1  -------------------- 68.5  --------------------                                                       -------- 79.9 --------          THT, mg.sup.(a) 529   176.3 352.7 529   705.4 529   0                         AlEt.sub.3 /TiI.sub.4 molar ratio                                                             2.5   -------------------- 3.0 --------------------                                                         --------  3.5 --------          THT/TiI.sub.4 molar ratio                                                                     30    10    20    30    40    30    0                         Reaction Time, hrs.sup.(b)                                                                    21    182/3 201/4 181/4 21    20    181/2                     Results                                                                       Polymer yield, %                                                                              12.5  74.1  73.1  78.2  76.1  83.2  90.0                      Polymer mol. wt × 10.sup.-.sup.3(c)                                                     335   165   200   250   460   340   225                       Polymer unsaturation                                                           Vinyl, %       2.7   7.4   4.9   4.0   3.0   6.2   5.6                        Cis, %         17.7  59.2  28.1  17.7  12.0  21.9  89.3                       Trans, %       79.5  33.4  78.4  78.4  85.0  71.9  5.1                       __________________________________________________________________________     .sup.(a) Added immediately after the AlEt.sub.3.                              .sup.(b) See Table VI, footnote (b).                                          .sup.(c) See Table VI, footnote (c).                                     

EXAMPLE 41

A polymerization was carried out as described in Example 26 except forthe substitution of an equimolar amount (715.4 mg) oftetrahydrothiopyran for the THT. The polymerization reaction was allowedto proceed for 17 hours after which time 76.8g. of a tough rubberypolymer was recovered. The mol. wt. of the polymer was found to be190,000 and the unsaturation distribution: vinyl -- 3.3%, cis-14.9%, andtrans-81.8%.

EXAMPLE 42

A polymerization was carried out as described in Example 33 except forthe substitution of an equimolar amount (920 mg) of tetrahydrothiopyranfor the THT. The polymerization reaction was allowed to proceed for 17hours after which time 63.1g. of a tough rubbery polymer was recovered.The mol. wt. of the polymer was found to be 225,000 and the unsaturationdistribution: vinyl -- 6.1%, cis-13.3%, and trans-80.6%.

What is claimed is:
 1. A hydrocarbon-soluble catalyst system consistingessentially of:a. TiCl₄ -AlI₃ ; b. an aluminum trialkyl where the alkylhas from 1-12 carbon atoms, the molar ratio of aluminum trialkyl toTiCl₄ -AlI₃ being in the range of from about 1.5:1 to about 4.5:1; andc. a Lewis base selected from the group consisting oftetrahydrothiophene, tetrahydropyran, tetrahydrofuran,tetrahydrothiopyran, and 2,5-dimethyl tetrahydrofuran, the mole ratio ofLewis base to TiCl₄ being in the range of 10:1 to 200:1.